How often should a car air-conditioning system be cleaned?

Our tech guru has the answer
by Ferman Lao | Aug 14, 2012

I just want to ask how often a car aircon should be cleaned. I am hesitant to have mine cleaned.

In the past, my car aircon would get smelly after each cleaning. It once smelled like a dead lizard, and even well-known brands of air freshener could hardly eliminate the odor. Even a famous car-aircon center in our neighborhood managed to cause flooding inside my car. Every day, I would bail water from inside the car.

I've been traumatized since then. Even aircon technicians in some popular gas stations cannot do a better job. Is it time to take a "degree" in aircon cleaning and make a DIY like Mr. Bean?

Thanks a lot!



Hi, Tolits. To better appreciate what goes on when we have our air-conditioning system cleaned, we need to know the basic aircon components. Most automotive aircon systems have a compressor, a filter/drier, a pressure switch, a condenser, an evaporator, and a thermostat. Some have a cabin filter and a heater core (for those with climate control systems or heaters).

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My own opinion of automotive aircon systems is that they are supposed to be sealed systems (similar to the refrigerators and aircon units found in our houses and offices), which shouldn't require any opening of the refrigerant lines until such a time when the lubricating oil inside the system breaks down enough to require replacement. However, because automotive aircon systems operate under a much harsher environment--being subject to more vibration and the occasional impact to the vehicle when going over potholes--the internal moving parts are subject to more wear and tear. This contaminates both the lubricating oil and the refrigerant leading to replacement much sooner than the aircon system would require if it were not mobile.

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Quite frankly, I'm of the "as long as it's cooling during summer, don't touch it" camp when it comes to auto aircons for the aforementioned reason.

However, because of our generally more polluted driving environment, our condensers and evaporators do get clogged with dirt, grime and gunk from various sources, including strong car fresheners, which evaporate and slowly migrate to coat the surface of the evaporators in the passenger cabin.

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When the external surfaces of either the condenser or the evaporator get clogged, their efficiency and airflow through them are reduced. This is normally the leading cause of aircon malfunction. The only way to remove the clogging is to physically remove them from the vehicles and subject them to cleaning agents in order to "melt" away the gunk coating them.

If the system is not assembled properly, you'll have all sorts of problems including what you've encountered. The water you're getting inside the cabin, for example, is most likely just a matter of the drain hose being improperly replaced. Either it has a kink or blockage that prevents water from flowing out, or it wasn't properly placed back. Like with most things that go wrong, the cause is usually substandard work, unfortunately.

You can, of course, do it yourself, as courses are certainly available out there. But it may be just more cost-efficient to find a reputable shop that takes pride in their work quality and hope for the best. Auto aircon servicing requires a number of expensive specialized equipment for it to be a practical DIY affair.

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Best regards,

Ferman Lao
Technical Editor

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